Methomyl oxime, m.p. 94.degree.-97.degree. C., is a commercial product (Aldrich 18,986-3 and is useful in the production of certain useful insecticides as the carbamate, Methomyl, and similar derivatives.
There are numerous references in the literature to the preparation of this economically useful intermediate and related alkyl thiolhydroxamates. Most of these prior art references are characterized by either low yields or high reaction dilutions. The yields have been low due to highly reactive nature of the reaction environment. To overcome this critical environmental factor, many of the prior art syntheses have been carried out at great dilution, thus the nature of the solvent and the degree of dilution are critical.
U.S. Pat. No. 3,987,096 discloses an aqueous process which gives yields of about 90% of methomyl oxime but at a reaction concentration of less than 1%. Such a low concentration hinders a viable production rate and is particularly wasteful of energy in the steps required for economic recovery of the valuable intermediate or its ultimate products.
Recently yields of similar magnitude of methomyl oxime have been reported in U.S. Pat. No. 3,752,841 where dimethylformamide (DMF) is used as the reaction solvent. This solvent permits reaction concentrations of about 20-25% and thus provides greater reaction efficiency. However DMF is a recognized irritant and toxicant substance requiring stringent precautions in the workplace under current safety legislation